Description: Length is typically 15 to 20 inches; possibly up to 33 inches. This is one of the smallest species of rattlesnakes in North America. The western pygmy rattlesnake is a small, colorful rattlesnake with a slender tail and tiny rattle. This is one of the smallest species of rattlesnake in North America. Its general color is brownish gray with small dark brown or black blotches. There are 20–30 dorsal blotches, which are round or in short bars. There are one or two alternating rows of small, rounded, dark blotches along the sides. A narrow orange-brown dorsal stripe is usually present. The head has a distinct black stripe that angles from the eye to the corner of the mouth and a sensory pit (heat-sensing pit) located between each nostril and eye. The slender tail has 6–8 dark bands and terminates in a small rattle. Its belly is dusky cream colored with numerous dark, irregularly spaced transverse bars. The scales along the back and sides are keeled, and the anal plate is single.

Habitat: They prefer a variety of habitats across their range, in Arkansas they are associated with cedar thickets, in Louisiana and east Texas they are found in dry pine uplands, and in Tennessee they are found around the edges of lakes and swamps.

Range: Sistrurus miliarius streckeri is found in the United States in Mississippi (except for southeast of the Pearl River Valley), west through Louisiana into eastern Texas, and north into southeastern and central Oklahoma, Arkansas, southern Missouri, and southwestern Tennessee.

Found in these States: AL | KS | LA | MO | MS | OK | TN | TX

Venom: Wright and Wright (1957) include excerpts from Allen (1938) that describe how an assistant was bitten by S. m. barbouri in the Everglades and suffered severe pain and swelling for about 24 hours despite treatment. Allen also quotes some statistics: according to the Florida Reptile Institute, 28 people were bitten by this subspecies in Florida between 1935 and 1937 with no deaths. Though these bites are painful, they are not considered life-threatening to people or pets.

The venom contain disintegrins, notably barbourin which has a KGD (Lys-Gly-Asp) amino acid motif rather than the more common RGD (Arg-Gly-Asp) motif. This single amino acid alteration gives barbourin higher binding affinity for the fibrinogen receptor glycoprotein IIb/IIIa. This receptor plays an important role in the aggregation of platelets, which then leads to the formation of a blood clot – competitive inhibition of this receptor by barbourin will decrease platelet aggregation, and thus reduce clotting.

Diet: Like all pygmy rattlesnake subspecies, they target a variety of prey including amphibians, lizards and rodents. Young are born with yellow-tipped tails to assisting in luring prey.

Reproduction: This rattlesnake will give birth to 3-7 young per litter, and the young can be as small as 4 inches long!

Status: Listed as Least Concern in view of its wide distribution, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category.

Taxonomy: